Addon Managers For
Flight Simulator
and Prepar3D

Addit! Pro For Prepar3D

When I try to install an addon I get some weird run time error 430, "Class does not support Automation or does not support expected interface".

If Addit! Pro reports run-time error 430, "Class does not support Automation or does not support expected interface", the ActiveX system file mscomctl.ocx could be the problem. That file might be damaged, incorrectly registered or mismatched with the components Addit! Pro expects to find on your system.

Replacing mscomctl.ocx with the version from Addit! Pro's distribution may solve this problem and restore Addit! Pro's functionality. Here is how to do it:

1. Download a fresh copy of Addit! Pro from ByteForge ( Be sure the version you download is the same as the version you have installed.
2. Create a temporary folder on your hard drive (e.g. "C:\APTEMP\") and unzip the contents of the Addit! Pro zip file to that folder.
3. Press the Windows Start button then select Search (or Find).
4. Search your Windows operating system drive for "mscomctl.ocx".
5. Once you locate your copy, which should be in your "\System32" folder (or "\System" folder), move (not copy) the file to a new temporary folder (e.g. "C:\PREVMSCOMCTL\").*
6. Start Addit! Pro. The Windows Installer should notice mscomctl.ocx is missing. It will either restore the file automatically or, if it cannot find apfsx.msi (or apfs2004.msi), it will ask for the Addit! Pro distribution folder. In that case point it to the folder you created in above (e.g. "C:\APTEMP\") then press OK.

The problem should be solved by these actions.

* Keep your original mscomctl.ocx file around for a while in case you notice problems with other applications.